• Journal of The Korean Astronomical Society
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• v.47 no.6
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• pp.235-253
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• 2014

Intensity interferometry, based on the Hanbury Brown-Twiss effect, is a simple and inexpensive method for optical interferometry at microarcsecond angular resolutions; its use in astronomy was abandoned in the 1970s because of low sensitivity. Motivated by recent technical developments, we argue that the sensitivity of large modern intensity interferometers can be improved by factors up to approximately 25 000, corresponding to 11 photometric magnitudes, compared to the pioneering Narrabri Stellar Interferometer. This is made possible by (i) using avalanche photodiodes (APD) as light detectors, (ii) distributing the light received from the source over multiple independent spectral channels, and (iii) use of arrays composed of multiple large light collectors. Our approach permits the construction of large (with baselines ranging from few kilometers to intercontinental distances) optical interferometers at the cost of (very) long-baseline radio interferometers. Realistic intensity interferometer designs are able to achieve limiting R-band magnitudes as good as $m_R{\approx}14$, sufficient for spatially resolved observations of main-sequence O-type stars in the Magellanic Clouds. Multi-channel intensity interferometers can address a wide variety of science cases: (i) linear radii, effective temperatures, and luminosities of stars, via direct measurements of stellar angular sizes; (ii) mass-radius relationships of compact stellar remnants, via direct measurements of the angular sizes of white dwarfs; (iii) stellar rotation, via observations of rotation flattening and surface gravity darkening; (iv) stellar convection and the interaction of stellar photospheres and magnetic fields, via observations of dark and bright starspots; (v) the structure and evolution of multiple stars, via mapping of the companion stars and of accretion flows in interacting binaries; (vi) direct measurements of interstellar distances, derived from angular diameters of stars or via the interferometric Baade-Wesselink method; (vii) the physics of gas accretion onto supermassive black holes, via resolved observations of the central engines of luminous active galactic nuclei; and (viii) calibration of amplitude interferometers by providing a sample of calibrator stars.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.1
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• pp.80-89
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• 2001

The objective of this study was to introduce the current status and development strategy for the environmental restoration of stream side in Japan, and to consider the methodology which could be effectively applied to the environmental restoration of stream side in Korea. 1. We should establish a new paradigm of forest conservation and erosion control which can emphasize the restoration of the stream side ecosystem and reduce soil movement in the areas. Also, in the past, the objective of forest conservation and erosion control was to fix soil by constructing permanent structures. The direction of future forest conservation and erosion control needs to be new forest conservation and erosion control technology to prevent large scale soil movement but allow small scale soil movement to conserve sound ecosystem and biotic habitats. 2. In the past, the goal of forest conservation and erosion control planning was to fix the amount of soil movement by constructing permanent facilities. Forest conservation and erosion control planning in the future needs to change the techniques which could prevent soil movement from large scale of soil disasters, but allow soil movement effectively to a small and middle scale's soil movement. Also, it is considered to change erosion control dams from non passing type to passing type. 3. In the point of ecological conservation aspects, we should evaluate the effects of new forest conservation and erosion control methods which are emphasized on the restoration of the stream side ecosystem. Also, forest conservation and erosion control construction projects for restoring stream and river ecosystem should be planned for perfectly restorating their ecosystems by the way of sustainable maintenance and management. 4. The restoration direction of stream and river ecosystems needs to be restoring the diversity of small geographies such as waterway, shoal and puddles rather than flattening stream bed. And the restoration of the stream side ecosystem should provide continuity of the stream side environment which allows desirable biological habitats, and environmentally sound facilities to harmonize with the environment.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.12
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• pp.5019-5024
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• 2015

Background: The purpose of this study was to assess the dosimetric and clinical feasibility of volumetric modulated arc based hypofractionated stereotactic radiotherapy (RapidArc) treatment for large acoustic schwannoma (AS >10cc). Materials and Methods: Ten AS patients were immobilized using BrainLab mask. They were subject to multimodality imaging (magnetic resonance and computed tomography) to contour target and organs at risk (brainstem and cochlea). Volumetric modulated arc therapy (VMAT) based stereotactic plans were optimized in Eclipse (V11) treatment planning system (TPS) using progressive resolution optimizer-III and final dose calculations were performed using analytical anisotropic algorithm with 1.5 mm grid resolution. All AS presented in this study were treated with VMAT based HSRT to a total dose of 25Gy in 5 fractions (5fractions/week). VMAT plan contains 2-4 non-coplanar arcs. Treatment planning was performed to achieve at least 99% of PTV volume (D99) receives 100% of prescription dose (25Gy), while dose to OAR's were kept below the tolerance limits. Dose-volume histograms (DVH) were analyzed to assess plan quality. Treatments were delivered using upgraded 6 MV un-flattened photon beam (FFF) from Clinac-iX machine. Extensive pretreatment quality assurance measurements were carried out to report on quality of delivery. Point dosimetry was performed using three different detectors, which includes CC13 ion-chamber, Exradin A14 ion-chamber and Exradin W1 plastic scintillator detector (PSD) which have measuring volume of $0.13cm^3$, $0.009cm^3$ and $0.002cm^3$ respectively. Results: Average PTV volume of AS was 11.3cc (${\pm}4.8$), and located in eloquent areas. VMAT plans provided complete PTV coverage with average conformity index of 1.06 (${\pm}0.05$). OAR's dose were kept below tolerance limit recommend by American Association of Physicist in Medicine task group-101(brainstem $V_{0.5cc}$ < 23Gy, cochlea maximum < 25Gy and Optic pathway <25Gy). PSD resulted in superior dosimetric accuracy compared with other two detectors (p=0.021 for PSD.

• The korean journal of orthodontics
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• v.20 no.2
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• pp.363-379
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• 1990

The purpose of this study was to evaluate the effects of the mandibular retractive force on the mandibular condyle of growing dog. The experimental animals were six mongrel dogs of two-month old. Their deciduous dentition were completed. Two of them was used as control group, and experimental group was composed of remaining four. Head band and chin cup were made of cotton tape, and hooks are fabricated on the chin cup and had band for closed coil. Mandibular retractive force was 100g/side and chin cap appliance was used for 14 hours/day during night. Experimental group were sacrificed at 2, 4, 6, 8 weeks from beginning of the experiment. Right TMJ was prepared for histologic study and left TMJ was examined grossly for disc, fossa, and condyle. The conclusions are: 1. Two-month old control animal showed active cartilaginous growth on the mandibular condyle, therefore showed thick proliferative and hypertrophic zones. Remodeling process in the condyle head was observed in which there were bone resorption on the anterior surface and bone apposition on the posterior surface. 2. Four-month old control animal showed marked reduction of hypertrophic zone but the condylar bone remodeling was more pronounced. 3. In experimental group, there are marked reduction of hypertrophic zone at 4 weeks from beginning of experiment, and hypertrophic zone disappeared at posterior-superior portion of condyle in 6-week experimental animal. 8 week experimental animal showed slight recovery of hypertrophic zone. 4. In experimental group, bone deposition was increased at anterior surface of condyle, and bone resorption was increased at posterior surface of condyle. 5. In control group, the glenoid fossa and surrounding bone showed mainly bone apposition. But experimental group showed bone resorption at anterior surface of articular eminence and increased bone apposition at posterior surface of postglenoid spine. 6. No marked traumatic change was seen but 4 weeks and 8 weeks experimental animal showed flattening of posterior surperior condylar surface. Bone marrow of condyle showed minute focal bleeding in 2 weeks and 4 weeks experimental animal, and congestion and depression of hematopoietic bone marrow during all experimental period.

• Progress in Medical Physics
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• v.27 no.3
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• pp.111-116
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• 2016

This study is to evaluate the dosimetric impact of dosimetric leaf gap (DLG) and transmission factor (TF) at different measurement depths and field sizes for high definition multileaf collimator (HD MLC). Consequently, its clinical implication on dose calculation of treatment planning system was also investigated for pancreas stereotactic body radiation therapy (SBRT). The TF and DLG were measured at various depths (5, 8, 10, 12, and 15 cm) and field sizes ($6{\times}6$, $8{\times}8$, and $10{\times}10cm^2$) for various energies (6 MV, 6 MV FFF, 10 MV, 10 MV flattening filter free [FFF], and 15 MV). Fifteen pancreatic SBRT cases were enrolled in the study. For each case, the dose distribution was recomputed using a reconfigured beam model of which TF and DLG was the closest to the patient geometry, and then compared to the original plan using the results of dose-volume histograms (DVH). For 10 MV FFF photon beam, its maximum difference between 2 cm and 15 cm was within 0.9% and it is increased by 0.05% from $6{\times}6cm^2$ to $10{\times}10cm^2$ for depth of 15 cm. For 10 MV FFF photon beam, the difference in DLG between the depth of 5 cm and 15 cm is within 0.005 cm for all field sizes and its maximum difference between field size of $6{\times}6cm^2$ and $10{\times}10cm^2$ is 0.0025 cm at depth of 8 cm. TF and DLG values were dependent on the depth and field size. However, the dosimetric difference between the original and recomputed doses were found to be within an acceptable range (<0.5%). In conclusion, current beam modeling using single TF and DLG values is enough for accurate dose calculation.

• Polymer(Korea)
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• v.30 no.1
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• pp.85-89
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• 2006

The effect of vapor grown carbon fiber (VGCF) contents on electrical and rheological properties of VGCF filled polyphenylene sulfide (PPS) composites prepared through melt mixing using a twin screw exruder was studied. This method was proved to be quite effective to produce good dispersion of VGCF in the matrix even for highly filled PPS. From the dependence of the electrical conductivity on VGCF content, the percolation phenomena began to occur above $10\;wt\%$. While there is only a marginal increase of viscosity for 1 and $5\;wt\%$ VGCF filled PPS, the composites containing $10\;wt\%$. While VGCF showed abrupt increase in viscosity as well as flattening of frequency vs modulus curve, indicating a transition from a liquid-like to a solid-like behavior due to the creation of VGCF network. This result agrees well to the fact that the network formation in the composite can be composite by rheological property dependence on filler content as well as by electrical conductivity measurement.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.571-575
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• 2016

Monte Carlo simulations are widely used as the most accurate technique for dose calculation in radiation therapy. In this paper, the GATE6(Geant4 Application for Tomographic Emission ver.6) code was employed to calculate the dosimetric performance of the photon beams from a linear accelerator(LINAC). The treatment head of a Varian 21EX Clinac was modeled including the major geometric structures within the beam path such as a target, a primary collimator, a flattening filter, a ion chamber, and jaws. The 6 MV photon spectra were characterized in a standard $10{\times}10cm^2$ field at 100 cm source-to-surface distance(SSD) and subsequent dose estimations were made in a water phantom. The measurements of percentage depth dose and dose profiles were performed with 3D water phantom and the simulated data was compared to measured reference data. The simulated results agreed very well with the measured data. It has been found that the GATE6 code is an effective tool for dose optimization in radiotherapy applications.

• Journal of Oral Medicine and Pain
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• v.34 no.1
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• pp.81-90
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• 2009

This study is designed to assess Relationship between clinical diagnosis of Temporomandibular Joint Disorder and diagnostic finding of Cone Beam Computed Tomography(CBCT) The author performed clinical examination for TMD Patients who visited Orofacial pain clinic, Jin-ju ooo Dental office. CBCT(Cone beam computed tomography) was taken for 190 joints in 95 subjects. A Oral medicine and Oral radiologist evaluated CBCT each other. then we compared with that result, Condyle bony changes were classified by no bone change, flattening, erosion and osteophyte. The obtained results were as follow: 1. The Kappa index of the diagnosis between oral medicine and oral radiogist were high, the index of diagnosis by degenerative joint disease were more higher. 2. The Kappa index of panoramic view and CBCT was low, more condylar bone chages were observed by CBCT diagnosis 3. Condylar bone changes of the 54.2% of non-DJD group clinicaly was observed by CBCT diagnosis and no bone changes of the 15.3% of DJD group.was observed by CBCT 4. TMJ pain was associated with erosion of condyle bone change of TMJ. Crepitation and longest duration of TMD were associated with osteophytic bone change.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.14 no.1
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• pp.121-134
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• 1984

The authors analyzed the morphological change of bone structure from 3,140 radiographs (1570 joints) of 785 patients with temporomandibular joint arthrosis, which were obtained by the oblique lateral transcranial projection and orthopantomographs. The interrelation of bone change and clinical symptoms, duration of the diseases were examined. Also, the bone changes of articular eminence, condyle, articular fossa were examined according to positional change of the condyle in the mouth open and close state. The results were as follows. 1. In the 785 patients with TMJ arthrosis, 782 patients (99.62%) show the positional change of the condyle. Among them 691 patients (88.03%) show the bone change. 2. In TMJ arthrosis patients with bone changes 451 patients (65.27%) showed both the condylar positional changes and bone changes bilaterally. 198 patients (28.65%) show the condylar positional changes bilaterally and bone changes unilaterally. 3. The bone changes in the TMJ arthrosis were in order of frequency eburnation (647 cases, 32.8%), erosion (548 cases, 27.79%), flattening (418 cases, 21.20%), deformity (138 cases, 6.99%). sclerosis (115 cases, 5.83%), marginal proliferation (106 cases, 5.38%). The region of bone change in TMJ arthrosis with condylar positional changes were in order of frequency the articular eminence (43.97%) condylar head (38.64%), articular fossa (17.39%). In the patients with bone changes, their clinical symptoms were pain (44.34%), clicking sound (33.5%), limitation of mouth opening (22.52%). In the patients complaining pain the most frequent bone change was erosion (28.60%), in the patients complaining clicking sound, eburnation (28.97%) in the patients complaining the limitation, eburnation (29.40%). Also in the patients with the duration below 1 year most common bone change was eburnation. 5. The most common condylar positional change was downward position (39.94%) in closed state, restricted movement of condyle (30.07%) in open state. The condylar positional changes and bone changes according to the region were as follows: a) In the condylar head the most frequent bone change was erosion (30.45%) and the most frequent condylar positional change was downward position (37.40%) in closed state, restricted movement of condyle (33.2%) in open state. b) In the articular eminence the most frequent bone change was eburnation (39.91%) and the most frequent condylar positional change was downward position (39.79%) in closed state, restricted movement of condyle (27.22%) in open state. c) In the articular fossa the most frequent bone change was eburnation (53.94%) and the most frequent condylar positional change was downward position (42.57%) in closed state, restricted movement of condyle (30.32%) in open state.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.108-109
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• 2003

Ursolic acid (UA) and Oleanolic acid (ONA), known as urson, micromerol, prunol and malol, are pentacyclic triterpenoid compounds which naturally occur in a large number of vegetarian foods, medicinal herbs, and plants. They may occur in their free acid form or as aglycones for triterpenoid saponins, which are comprised of a triterpenoid aglycone, linked to one or more sugar moieties. Therefore UA and ON A are similar in pharmacological activity. Lately scientific research, which led to the identification of UA and ONA, revealed that several pharmacological effects, such as antitumor, hepatoprotective, anti-inflammatory, antimicrobial, and anti-hyperlipidemic could be attributed to UA and ONA. Here, we introduced the effects of UA and ONA on acute barrier disruption and normal epidermal permeability barrier function. To clarify the effects of UA and ONA on skin barrier recovery, both flank skin of 8-12 weeks hairless mice were topically treated with samples (2mg/ml) after tape stripping, then measured recovery rate using TEWL on hairless mice. The recovery rate increased in UA and ONA treated groups at 6h more than 20% compared to vehicle treated group (p <0.05). For verifying the effects of UA and ONA on normal epidermal barrier, hydration and TEWL were measured for 1 and 3 weeks after UA and ONA applications (2mg/ml per day). We also investigated the features of epidermis and dermis using electron microscopy (EM) and light microscopy (LM). Both samples increased hydration compared to Vehicle group from 1 week without TEWL alteration (p<0.005). EM examination using Ru04 and OsO4 fixation revealed that secretion and numbers of lamellar bodies and complete formation of lipid bilayers were most prominent (ONA$\geq$UA>Vehicle). LM finding showed that stratum corneum was slightly increased and especially epidermal thickening and flattening was observed (UA>ONA>Vehicle). Using Masson-trichrome and elastic fiber staining, we observed collagen thickening and elastic fiber increasing by UA and ONA treatments. In vitro results of collagen and elastin synthesis and elastase inhibitory experiments were also confirmed in vivo findings. This result suggested that the effects of UA and ONA related to not only skin barrier but also collagen and elastic fibers. Taken together, UA and ONA can be relevant candidates to improve barrier function and pertinent agents for cosmetic applications.